The present invention relates to the technical field of cleaning compositions for glass surfaces and in particular, compositions that reduce the glass corrosion during the automatic cleaning of glass surfaces.
Damage to the surface of glassware during cleaning and/or rinsing procedures is a long known problem which is based firstly on the loss of minerals from the glass composition due to hydrolysis of the silicate network and secondly due to a deposition of silicate material onto the glassware.
Automatic dishwashing can be considered as a specific case of this occurrence, as for example a consumer knows from washing glassware in a typical domestic dishwasher. In particular, the repeated washing of glassware in a dishwasher can cause the above-depicted phenomena to damage the glass surfaces resulting in cloudiness, scratches, smears or the like. These types of adverse effects on the appearance of machine washed glassware illustrate still today one of the most frequent problems encountered with automatic cleaning compositions.
In the prior art, the use inter alia of zinc is proposed to overcome the above problems. For example, the document EP 0 383 482 describes automatic dishwasher cleaning compositions comprising insoluble zinc salts which are characterized by an improved protection against glass corrosion. In order to produce this effect, the insoluble zinc salts must have a particular particle size.
WO 00/39259 discloses water-soluble glasses according to DIN ISO 719 which comprise at least one glass corrosion inhibitor, whose weight fraction in the glass is not more than 85 wt. % and which is released under the conditions of the cleaning and/or rinsing cycles.
However, the compositions known from the prior art are not fully satisfactory. Sometimes they have the disadvantage that they can only be used in the pre-cleaning or main cleaning cycles, or then only act in the rinse cycle when the consumer places a product such as the glasses of the WO 00/39259 in the automatic dishwasher. Sometimes they can indeed be used in the rinse cycle but their performance is unsatisfactory.
U.S. Pat. No. 6,423,661 B1 describes silyl-terminated prepolymers that are manufactured by reacting an isocyanate-silane with the OH groups of a polyether polyol that can possess up to eight arms. The resulting prepolymers of the cited compounds find use in adhesives. A use of the prepolymers, for example in cleaning compositions or for the corrosion protection of glass, has not been disclosed.
A polyurethane prepolymer having terminal alkoxy silane groups and hydroxyl groups is known from US 2003/0153712 A1. For their manufacture, a polyether diol is initially treated with a stoichiometric deficiency of diisocyanate, and the silyl groups are then introduced by further treating the resulting isocyanate-hydroxy compound with an amino silane. The described two armed polyalkoxylates in the form of prepolymers are used in the manufacture of sealants and adhesives.
US 2004/0096507 A1 deals with six-armed polyethylene glycol derivatives and discloses a fully silyl terminated derivative that can be manufactured from: sorbitol as the central moiety. The polyethylene glycol derivatives described in the document are intended to be suitable for manufacturing biologically degradable polymeric hydrogels and for use in the medical/pharmaceutical field for implants.